staging: hisilicon,hi6421-spmi-pmic.yaml: fix patternProperties

The regex at the patternProperties is wrong, although this was
not reported as the DT schema was not enforcing properties.

Fix it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/46b2f30df235481cb1404913380e45706dfd8253.1626515862.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>